The invention applies in particular, but not exclusively, to the achievement of guiding devices for strands of cables which, made up of a multiplicity of strands, are used in civil engineering and building activities.
In fact, numerous structures in the field and notably bridges comprise cables which are used in particular to support elements of these structures and/or hold them between them.
Such cables are stressed in traction between their opposite ends, but frequently guiding devices are used for holding them laterally and locally in such a manner as to deviate them in whatever way in the direction in which they must extend.
The function of a guiding device of the type cited above is thus to permit lateral and local holding of a cable and transfer of the stress caused by this deviation to a support provided for this purpose.
A guiding device of the aforementioned type is intended to be interposed between the support and the cable.
Conventionally, such a guiding device is conceived to allow individual lateral and local support of each strand of cable.
To this end, a guiding device comprises at least one bearing area for guiding for a strand of cable, and preferably a plurality of bearing areas for deviation, each permitting the individual support of one of the strands of a cable.
A guiding device is made up of a body, generally solid, in which at least one curved channel is made, referred to as channel, intended to be traversed by the strand.
The body conventionally comprises at least as many channels as the guide cable comprises strands.
Conventionally, the strands are each made up of a multiplicity of wires, generally metallic, but not limited thereto.
The strands often have a cross section which is inscribed in a circle, but this section can also be oval or of another shape.
The channels each have a cross section of substantially complementary shape to that of the strand which they must receive.
For example, when the strands of the cable each have a cross section which inscribes a circle, each channel has a cross section substantially circular of a diameter greater than the circle in which the cross section of a strand is inscribed.
It can be borne in mind that each channel of the body comprises a curved longitudinal axis and at least one first part which, situated in principle at the side of the intrados of the longitudinal axis, permits, within the limit of the length of the channel, the support of the strand on a portion of the peripheral face of said strand.
It can likewise be borne in mind that each channel comprises at least a second part which, situated in principle at the side of the extrados of the longitudinal axis, is connected to the first part and enables guiding the strand during its engagement in the channel in order to shape it in a plane of curvature that contains the longitudinal axis of said channel.
Designated by longitudinal axis is an axis which extends along the longitudinal dimension of the channel, but not obligatorily in a median position with respect to the transverse dimension of the channel in a plane of curvature of this channel.
The longitudinal axis indicated has as a function to permit the definition of an intrados and of an extrados, the intrados being a first zone situated on the inside of the curve formed by this longitudinal axis, and the extrados being a second zone situated on the exterior of the curve formed by said longitudinal axis.
Conventionally, each channel is of circular cross section.
Referring to the illustration, the body of the device is made up of a mass of concrete, and each channel is formed by the passage of a curved tube embedded in said concrete mass.
Whatever the case may be, the devices of this type have their advantages, but one very much regrets that the strands which traverse these guiding devices can displace themselves axially, after mounting, and when they are under load and subjected to variations in tension from one side or the other of the guiding device.